Typically, awnings, canopies, coverings, displays, and other similar structures are constructed of an elongated frame or support structure to which a covering material is anchored. The frame is conventionally constructed of a stiff, yet malleable light-weight material such as aluminum, in order to achieve a variety of special shapes. The frame is usually rectangular in vertical cross-section, and has a longitudinal slot, or channel, extending the length of the frame, within which the closure material is anchored, for example by a staple. The construction generally attempts to offer flexibility of form in that the frame members can be bent to produce closure assemblies having arcuate shapes.
However, the prior art has failed to eliminate the problem of twisting and warping of the frame members that occurs when they are bent into the desired forms. This misshaping occurs due to the opposed compression and tension forces applied to the hollow frame member during arcuate bending. This frame misshaping may also prevent access to the closure anchoring slot in the frame member due the "cupping effect." This necessitates reopening the slot by hand, which is laborious and adds further inconsistencies to the final frame shape. Accordingly, it is a goal of the present invention to provide a self-stabilizing extrusion for closure assemblies which maximizes stabilization against misshaping due to bending, while minimizing the overall weight of the extrusion.